A Secretarty?
It sends Reminder emails for upcoming deadlines, overdue items, or change of item status
A Guarder?
It sends Alert email to SharePoint users/groups when items are created, modified or deleted.

On top of that, you can define complex Alert/Reminder conditions which are useful yet do not exist in OTB SharePoint. You can also customize the body of the email. More features of this great solution, please visit SharePoint Alert Reminder